date literals

I think the date literal should allow a trailing 'Z' to substitute for
'+00:00'. This form is used quite a bit by authors producing similar
profiles, such as W3C-DTF, RFC3339, and XML Schema. Web authors will
have to accept the form, so the parse method should support it.
It looks like the grammar allows an offset of '-00:00'. That may not
be desirable. Here's some background on the edge cases of this family
of date format:
<http://www.imc.org/atom-syntax/mail-archive/msg13103.html>
"RFC 3339 gives a different semantic to a timezone offset of -00:00
from +00:00 and Z which xsd:dateTime (and to the best of my knowledge
ISO 8601) doesn't. Sect 4.3 of RFC 3339 reads:"
If the time in UTC is known, but the offset to local time is
unknown, this can be represented with an offset of "-00:00". This
differs semantically from an offset of "Z" or "+00:00", which
imply that UTC is the preferred reference point for the specified
time.
--
Robert Sayre